VLF vs. Pulse Induction: Which Technology and When
VLF (Very Low Frequency) and PI (Pulse Induction) are the two main detector technologies. They work on different principles and have different strengths, which makes them suited to different types of detecting.
VLF (Very Low Frequency)
VLF detectors use a continuous transmit/receive cycle and can discriminate between target types based on conductivity and ferrous properties. This is what most detectors use, including nearly all beginner and mid-range machines.
Strengths: Target discrimination, iron rejection, precise target ID, lower cost, lighter weight.
Weaknesses: Affected by ground mineralization (especially salt water and volcanic soils), generally less depth than PI on large targets.
Pulse Induction (PI)
PI detectors send short, powerful pulses of current and measure the decay time of the resulting signal. They ignore ground mineralization almost completely, which makes them the technology of choice for challenging ground.
Strengths: Extreme depth on some target types, excellent in mineralized ground and salt water, great for beach detecting in wet sand and surf.
Weaknesses: Limited or no discrimination (you dig everything), heavier, more expensive, higher battery consumption.
Which to Choose
For general detecting — coins, relics, jewelry in parks, yards, and fields — VLF is the right choice. Discrimination is essential when you're detecting areas with mixed targets. For beach hunting in salt water, gold prospecting, and situations where extreme depth matters more than discrimination, PI is worth the investment.